A backlight module is one of the key subassemblies in a liquid crystal display panel. Generally, a backlight module includes a back plate, and a reflective sheet, a light guide plate and a diffusing layer which are disposed on the back plate. A backlight module can be provided with a liquid crystal cell including an array substrate, an opposed substrate and a liquid crystal layer sandwiched between the array substrate and the opposed substrate thereon. Thus, the backlight module can provide uniformly-distributed backlight with sufficient brightness to the liquid crystal cell.
As illustrated by FIG. 1 and FIG. 2, the structure of an ordinary backlight module includes a reflective layer 002, a light guide plate 003, a diffusing layer 004 and the like, which are sequentially disposed on a back plate 001. A backlight module can be further provided with a module frame 005 thereon. A display panel 009 is disposed on the module frame 005, and finally constitutes a rudiment of a display device together with an assembling frame 007 and the backlight module. In this structure, in order to conveniently assemble the relative components, a certain gap will be remained between different components (for example, a light guide plate 003 and a position limit structure 006); besides, with regard to a light guide plate which is sensitive to the surrounding changes such as temperature and humidity, in order to guarantee a certain reliability on the temperature and humidity, the width of the gap can be determined according to a predicted expansion amount in design.